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-rw-r--r--drivers/cpufreq/intel_pstate.c2
-rw-r--r--include/linux/cpufreq.h7
-rw-r--r--include/linux/tick.h1
-rw-r--r--kernel/sched/cpufreq_schedutil.c82
-rw-r--r--kernel/time/tick-sched.c12
5 files changed, 76 insertions, 28 deletions
diff --git a/drivers/cpufreq/intel_pstate.c b/drivers/cpufreq/intel_pstate.c
index c31b72b16c2b..b7de5bd76a31 100644
--- a/drivers/cpufreq/intel_pstate.c
+++ b/drivers/cpufreq/intel_pstate.c
@@ -41,6 +41,7 @@
#define INTEL_PSTATE_HWP_SAMPLING_INTERVAL (50 * NSEC_PER_MSEC)
#define INTEL_CPUFREQ_TRANSITION_LATENCY 20000
+#define INTEL_CPUFREQ_TRANSITION_DELAY 500
#ifdef CONFIG_ACPI
#include <acpi/processor.h>
@@ -2237,6 +2238,7 @@ static int intel_cpufreq_cpu_init(struct cpufreq_policy *policy)
return ret;
policy->cpuinfo.transition_latency = INTEL_CPUFREQ_TRANSITION_LATENCY;
+ policy->transition_delay_us = INTEL_CPUFREQ_TRANSITION_DELAY;
/* This reflects the intel_pstate_get_cpu_pstates() setting. */
policy->cur = policy->cpuinfo.min_freq;
diff --git a/include/linux/cpufreq.h b/include/linux/cpufreq.h
index 87165f06a307..a5ce0bbeadb5 100644
--- a/include/linux/cpufreq.h
+++ b/include/linux/cpufreq.h
@@ -120,6 +120,13 @@ struct cpufreq_policy {
bool fast_switch_possible;
bool fast_switch_enabled;
+ /*
+ * Preferred average time interval between consecutive invocations of
+ * the driver to set the frequency for this policy. To be set by the
+ * scaling driver (0, which is the default, means no preference).
+ */
+ unsigned int transition_delay_us;
+
/* Cached frequency lookup from cpufreq_driver_resolve_freq. */
unsigned int cached_target_freq;
int cached_resolved_idx;
diff --git a/include/linux/tick.h b/include/linux/tick.h
index a04fea19676f..fe01e68bf520 100644
--- a/include/linux/tick.h
+++ b/include/linux/tick.h
@@ -117,6 +117,7 @@ extern void tick_nohz_idle_enter(void);
extern void tick_nohz_idle_exit(void);
extern void tick_nohz_irq_exit(void);
extern ktime_t tick_nohz_get_sleep_length(void);
+extern unsigned long tick_nohz_get_idle_calls(void);
extern u64 get_cpu_idle_time_us(int cpu, u64 *last_update_time);
extern u64 get_cpu_iowait_time_us(int cpu, u64 *last_update_time);
#else /* !CONFIG_NO_HZ_COMMON */
diff --git a/kernel/sched/cpufreq_schedutil.c b/kernel/sched/cpufreq_schedutil.c
index 54c577578da6..76877a62b5fa 100644
--- a/kernel/sched/cpufreq_schedutil.c
+++ b/kernel/sched/cpufreq_schedutil.c
@@ -61,6 +61,11 @@ struct sugov_cpu {
unsigned long util;
unsigned long max;
unsigned int flags;
+
+ /* The field below is for single-CPU policies only. */
+#ifdef CONFIG_NO_HZ_COMMON
+ unsigned long saved_idle_calls;
+#endif
};
static DEFINE_PER_CPU(struct sugov_cpu, sugov_cpu);
@@ -93,22 +98,23 @@ static void sugov_update_commit(struct sugov_policy *sg_policy, u64 time,
{
struct cpufreq_policy *policy = sg_policy->policy;
+ if (sg_policy->next_freq == next_freq)
+ return;
+
+ if (sg_policy->next_freq > next_freq)
+ next_freq = (sg_policy->next_freq + next_freq) >> 1;
+
+ sg_policy->next_freq = next_freq;
sg_policy->last_freq_update_time = time;
if (policy->fast_switch_enabled) {
- if (sg_policy->next_freq == next_freq) {
- trace_cpu_frequency(policy->cur, smp_processor_id());
- return;
- }
- sg_policy->next_freq = next_freq;
next_freq = cpufreq_driver_fast_switch(policy, next_freq);
if (next_freq == CPUFREQ_ENTRY_INVALID)
return;
policy->cur = next_freq;
trace_cpu_frequency(next_freq, smp_processor_id());
- } else if (sg_policy->next_freq != next_freq) {
- sg_policy->next_freq = next_freq;
+ } else {
sg_policy->work_in_progress = true;
irq_work_queue(&sg_policy->irq_work);
}
@@ -192,6 +198,19 @@ static void sugov_iowait_boost(struct sugov_cpu *sg_cpu, unsigned long *util,
sg_cpu->iowait_boost >>= 1;
}
+#ifdef CONFIG_NO_HZ_COMMON
+static bool sugov_cpu_is_busy(struct sugov_cpu *sg_cpu)
+{
+ unsigned long idle_calls = tick_nohz_get_idle_calls();
+ bool ret = idle_calls == sg_cpu->saved_idle_calls;
+
+ sg_cpu->saved_idle_calls = idle_calls;
+ return ret;
+}
+#else
+static inline bool sugov_cpu_is_busy(struct sugov_cpu *sg_cpu) { return false; }
+#endif /* CONFIG_NO_HZ_COMMON */
+
static void sugov_update_single(struct update_util_data *hook, u64 time,
unsigned int flags)
{
@@ -200,6 +219,7 @@ static void sugov_update_single(struct update_util_data *hook, u64 time,
struct cpufreq_policy *policy = sg_policy->policy;
unsigned long util, max;
unsigned int next_f;
+ bool busy;
sugov_set_iowait_boost(sg_cpu, time, flags);
sg_cpu->last_update = time;
@@ -207,40 +227,37 @@ static void sugov_update_single(struct update_util_data *hook, u64 time,
if (!sugov_should_update_freq(sg_policy, time))
return;
+ busy = sugov_cpu_is_busy(sg_cpu);
+
if (flags & SCHED_CPUFREQ_RT_DL) {
next_f = policy->cpuinfo.max_freq;
} else {
sugov_get_util(&util, &max);
sugov_iowait_boost(sg_cpu, &util, &max);
next_f = get_next_freq(sg_policy, util, max);
+ /*
+ * Do not reduce the frequency if the CPU has not been idle
+ * recently, as the reduction is likely to be premature then.
+ */
+ if (busy && next_f < sg_policy->next_freq)
+ next_f = sg_policy->next_freq;
}
sugov_update_commit(sg_policy, time, next_f);
}
-static unsigned int sugov_next_freq_shared(struct sugov_cpu *sg_cpu,
- unsigned long util, unsigned long max,
- unsigned int flags)
+static unsigned int sugov_next_freq_shared(struct sugov_cpu *sg_cpu)
{
struct sugov_policy *sg_policy = sg_cpu->sg_policy;
struct cpufreq_policy *policy = sg_policy->policy;
- unsigned int max_f = policy->cpuinfo.max_freq;
u64 last_freq_update_time = sg_policy->last_freq_update_time;
+ unsigned long util = 0, max = 1;
unsigned int j;
- if (flags & SCHED_CPUFREQ_RT_DL)
- return max_f;
-
- sugov_iowait_boost(sg_cpu, &util, &max);
-
for_each_cpu(j, policy->cpus) {
- struct sugov_cpu *j_sg_cpu;
+ struct sugov_cpu *j_sg_cpu = &per_cpu(sugov_cpu, j);
unsigned long j_util, j_max;
s64 delta_ns;
- if (j == smp_processor_id())
- continue;
-
- j_sg_cpu = &per_cpu(sugov_cpu, j);
/*
* If the CPU utilization was last updated before the previous
* frequency update and the time elapsed between the last update
@@ -254,7 +271,7 @@ static unsigned int sugov_next_freq_shared(struct sugov_cpu *sg_cpu,
continue;
}
if (j_sg_cpu->flags & SCHED_CPUFREQ_RT_DL)
- return max_f;
+ return policy->cpuinfo.max_freq;
j_util = j_sg_cpu->util;
j_max = j_sg_cpu->max;
@@ -289,7 +306,11 @@ static void sugov_update_shared(struct update_util_data *hook, u64 time,
sg_cpu->last_update = time;
if (sugov_should_update_freq(sg_policy, time)) {
- next_f = sugov_next_freq_shared(sg_cpu, util, max, flags);
+ if (flags & SCHED_CPUFREQ_RT_DL)
+ next_f = sg_policy->policy->cpuinfo.max_freq;
+ else
+ next_f = sugov_next_freq_shared(sg_cpu);
+
sugov_update_commit(sg_policy, time, next_f);
}
@@ -473,7 +494,6 @@ static int sugov_init(struct cpufreq_policy *policy)
{
struct sugov_policy *sg_policy;
struct sugov_tunables *tunables;
- unsigned int lat;
int ret = 0;
/* State should be equivalent to EXIT */
@@ -512,10 +532,16 @@ static int sugov_init(struct cpufreq_policy *policy)
goto stop_kthread;
}
- tunables->rate_limit_us = LATENCY_MULTIPLIER;
- lat = policy->cpuinfo.transition_latency / NSEC_PER_USEC;
- if (lat)
- tunables->rate_limit_us *= lat;
+ if (policy->transition_delay_us) {
+ tunables->rate_limit_us = policy->transition_delay_us;
+ } else {
+ unsigned int lat;
+
+ tunables->rate_limit_us = LATENCY_MULTIPLIER;
+ lat = policy->cpuinfo.transition_latency / NSEC_PER_USEC;
+ if (lat)
+ tunables->rate_limit_us *= lat;
+ }
policy->governor_data = sg_policy;
sg_policy->tunables = tunables;
diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
index 7fe53be86077..64c97fc130c4 100644
--- a/kernel/time/tick-sched.c
+++ b/kernel/time/tick-sched.c
@@ -993,6 +993,18 @@ ktime_t tick_nohz_get_sleep_length(void)
return ts->sleep_length;
}
+/**
+ * tick_nohz_get_idle_calls - return the current idle calls counter value
+ *
+ * Called from the schedutil frequency scaling governor in scheduler context.
+ */
+unsigned long tick_nohz_get_idle_calls(void)
+{
+ struct tick_sched *ts = this_cpu_ptr(&tick_cpu_sched);
+
+ return ts->idle_calls;
+}
+
static void tick_nohz_account_idle_ticks(struct tick_sched *ts)
{
#ifndef CONFIG_VIRT_CPU_ACCOUNTING_NATIVE
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